It is proposed to prepare and investigate monofunctional and bifunctional aminoacyl derivatives of adenine-adenine and cytosine-adenine bridged ribonucleosides as potential transition state (multisubstrate) analogs of procaryotic ribosomal peptidyltransferase. The biological activity will be correlated with base stacking parameters of the parent model compounds obtained from hypochromism measurements and circular dichroism spectra. New synthetic methods for preparing oligonucleotide derived from bridged ribonucleosides and aminoacyl nucleosides with restricted mobility of amino acid moiety will be elaborated.